Rotary step-by-step actuator



Sept. 5, 1967 w. PARlsoE 3,340,411

ROTARY STEPBY-STEP ACTUATOR Filed- 0G12. 26. 1964 United States Patent O3,340,411 ROTARY STEP-BY-STEP ACTUATOR .Wilbert Parisoe, Highland Park,Ill., assignor to Oak Electro/Netics Corp., a corporation of DelawareFiled Oct. 26, 1964, Ser. No. 406,304 Claims. (Cl. S10-49) Thisinvention rel-ates in general to a rotary actuator, and moreparticularly to a rotary actuator which may be operated in astep-by-step manner to effect a desired switching operation.

In known types of rotary actuators, it has been conventional to employ arotary solenoid mechanism wherein means are provided for of a `plungerinto the desired rotary movement. This type of actuator has proven to beundesirable in certain res pects, in that it has necessitated the use ofrather cornplex mechanism in order to produce the desired results.Accordingly, the general purpose of the present invention is t-o providea rotary actuator wherein the actuator shaft rotates without axialmovement so as to obviate the need for rather complicated mechanisms toconvert the axial vmovement of a solenoid plunger into a desired rotarymovement. To attain this, the applicant has associated a novel stepmotor in combination with novel rotary actuator means in a manner so asto improve the operating characteristics of the rotary actuator.

An object of the present invention is to provide a rotary actuator witha novel step -motor so that the step motor can be assembled and operatedn a trouble-free manner, thus contributing to the improved output of therotary actuator.

Another object of the invention is to provide a step motor for a rotaryactuator as described in the preceding paragraph with an improvedterminal block construction so that the terminal block can be assembledinto the step motor in an efficient manner.

A further object of the invention is to provide a rotary actuatorutilizing a rotary step motor for step-by-step operation with a novelinterruptor switch for interrupting the excitation of the motor field.

Still another object is to provide a step motor operated rotary actuatorwith toggle interrupter means for opening and closing an interrupterswitch at definite and predetermined angles.

.A still further object of the invention is to provide a rotary actuatoras defined in the preceding paragraph with an interrupter switch whereinthe angle at which the switch opens is adjustable.

These and other objects of the invention will hereinafter become morefully apparent from the following description, taken in connection withthe annexed drawings, Wherein:

FIGURE 1 is a side elevational view of bodiment of the invention;

FIGURE 2 is a sectional view taken generally along line 2-2 of FIGURE l;

FIGURE 3 is a sectional view taken generally along the line 3-3 ofFIGURE l;

FIGURE 4 is a fragmentary side view of the rotary actuator illustratedin FIGURE l, taken from a different side from that shown in FIGURE l;

FIGURE 5 is a fragmentary sectional view taken generally centrallythrough the rotary actuator, with certain parts broken away for clarity;

FIGURE 6 is a sectional View taken generally along line 6 6 of FIGURE 5;

FIGURE 7 is a sectional line 7--7 of FIGURES;

FIGURE 8 is a sectional view taken generally along line 8 8 of FIGURE 5;and

a preferred emview taken generally along converting the axial movement lFIGURE 9 is a view similar to FIGURE 3 showing a modified form ofnterrupter switch mechanism.

While this invention is susceptible of embodiment in many differentforms, there is shown in the drawings and will herein be described indetail one specific embodiment and a modification thereof, with theunderstanding that the present disclosure is t-o be considered as anexemplification of the principles of the invention and is not intendedto limit the invention to the embodiments illustrated. The scope of theinvention will be pointed out in the appended claims.

Referring now to the drawings, wherein like reference charactersdesignate like or corresponding parts throughout the several views, therotary actuator embodiment illustrated in FIGURE l includes a step motorhoused in a suitable casing 20. As may be best seen in FIGURES 5, 7 and8 the step motor includes a stator indicated generally at 21, and arotor indicated generally at 22. The stator 21 is formed of threesections 23, 24 and 25, with sections 23 and 25 being generallyidentically shaped and best illustrated in FIGURE 7. The shape ofsection 24 is best illustrated in FIGURE 8. Each of sections 23-25 isgenerally rectangular in cross-section, and each section hasapproximately the same outer dimensions, so that they will snugly fitwithin casing 20. Each of sections 23-25 is provided with a hole 26adjacent each corner thereof, and a mounting stud 27 extends througheach of the aligned holes to retain the sections 23-25 in their desiredassembled relationship. The forward ends of studs 27 extend outwardlyfrom the forward end of the casing 20, so that the rotary actuator maybe mounted to a support, not shown. Each of the sections 23-25 includesrespective parallel faces 23a-23h, 24a-24h and 25a-25h. As can be bestseen in FIGURE 5, faces 23b and 24a are positioned in abuttingrelationship, while faces 24b and 25a are also positioned in abuttingrelationship. A front wall 28 abuts against face 25b, while a rear Wall29 abuts against face 23a. Walls 28 and 29 define the front and rearwalls of the casing 20, and will hereafter be more fully described.

Since sections 23 and 25 are identical, a detailed description will begiven of section 25 only, with it being understood that correspondingparts are also provided on section 23. A central bore 31 is provided insection 25 for reception of rotor 22, and the axis of bore 31 ispositioned at right angles to the plane of faces 25a and 2511. Aplurality of radial openings or notches 32 are provided around bore 31,to -define therebetween a plurality of poles 33. Poles 33 areequiangularly spaced around bore 31, and any number may be provided,with five being shown in FIGURE 7 for purposes of illustration only. Itwill be understood, of course, that stator sections 23 and 25 are formedof a material having effective magnetic properties, such as, forexample, pressed and sintered pure iron powder.

As can be best seen in FIGURE 8, stator section 24 is provided with acentral bore 34 of relatively large diameter, so that section 24 isshaped generally in the form of an annulus. Annular section 24 isdiscontinuous in that an opening 35 is provided in the upper portionthereof. Opening 35 is defined by facing surfaces 36 and 37, each ofwhich has an aligned respective dovetail slot 38 and 39, for receptionof a terminal block to be hereafter described. Like sections 23 and 25,section 24 is also formed of a material having effective magneticproperties, such as pressed and sintered 100% pure iron powder or theequivalent. A coil 41 is carried by a suitable coil bobbin which isfixed within `bore 34. The inner diameter 42 of the coil bobbin issubstantially the same as the inner diameter of bore 31, and the rotor22 is spaced from the bobbin and from the bore 31, so that it is free torotate relative to Ithe stator. It will be understood, of course, thatthe coil 41 is formed of a length of wire having opposite ends, each ofwhich is adapted to be connected to a source of direct current power,not shown. To this end, a terminal block 44 is provided, having a pairof terminals 45 and 46 to which the respective ends of the wire areadapted to be secured. As can be best seen in FIGURE 8, suitabledovetail extensions are provided on opposed faces 47 and 48 of theterminal block, and are slidably received within the dovetail recesses38 and 39. The complementarily shaped dovetailed portions on theterminal block 44 and the stator section 24 are sized so as to provide asliding iit between the terminal block and the stator section. Thus, theterminal block can be slid in place in stator section 24 withoutdifficulty. As can be best seen in FIGURE 5, terminal block 44 has awidth which is substantially the `same as the thickness of statorsection 24, so that the terminal block is firmly held in place betweenthe faces 23b and 25a of stator sections 23 and 25 respectively, whenthe stator unit is assembled. As is well known in the art, terminalblock 44 is formed of a suitable insulating material.

Rotor 22 is a generally cylindrical member, and includes a plurality ofgenerally radially extending, axially elongated poles 51. Rotor 22 ismovable between two positions, with the first or normal position beingshown in FIGURES 7 and 8. In the normal position, each pole 51 isypositioned in `general alignment with an opening 32 between adjacentstator poles 33, with each pole 51 being offset a slight angular amount,as for example toward the adjacent stator pole 33 in a clockwisedirection. Thus, when the iield coil 41 is energized, the rotor poles 51will be attracted to their closest stator poles 33, and the -rotor 51will rotate in a clockwise direction as viewed in FIGURES 7 and 8 sothat the rotor poles 51 are in the second position in radial alignmentwith the stator poles 33. When the stator eld 41 is deenengized, meansto be hereafter described will return the rotor 22 to the first orinitial position.

Rotor 22 inclu-des a central bore 52 which extends axially therethrough,and is adapted to slidably receive an actuator shaft 53. Forward casingwall 28 includes a central openin-g defined by a rearwardly extendingannular flange 54 which serves as a irst bearing for the forward endofshaft 53. The front face of the rotor 22 is provided with acountersunk portion 55 to accommodate the flange 54. The rear casingwall 29 is provide-d with a central opening defined by an annular flange56 which extends rearwardly from the wall 29, and which forms a secondbearing for shaft 53.

A second bore 57 is provided in rotor 22 at the rearward end thereof,and is offset from and eccentric to bore 52. A drive pin 58v is receivedin bore 57, and extends rearwardly from plate 29 through a rectangularopening 59 (FIGURE 6). Opening 59 is anked by a pair of tabs 61 whichextend rearwardly from plate 29 at generally right angles thereto.

A suitable stop member 62 is provided with aligned slots which areimpaled by tabs 61 to mount the stop 62 upon plate 29. An elongateopening is provided in stop member 62, and includes a generally circularlower portion 63 which receives flange 56, and an enlarge-d upperportion 64 in which pin 58 is free to move. As can be best seen inFIGURE 6, the sides of the opening portion 64 confine pin 58 to alimited degree of movement, and thus when the current flow to the coil41 is interrupted, the member 62 will positively locate the lrotor 22 inthe Icorrect initial vor first position as the drive pin 58 moves intoengagement with the side of stop 62.

Means are provided to interrupt the flow of current to the coil 41, toeffect the desired step-by-step operation of the actuator, and include aswitch carried by a mounting plate 66. Mounting plate 66 is held inspaced `relation with respect to the rea-r casing wall 29 by a pair ofcylindrical spacing members 67, which are received in aper-v turedbosses 68 in the rear casing wall 29. Spacing members 67 may be providedwithV an internally threaded bore, as may be best seen at 70 in FIGURE5, for reception of the threaded end of longitudinally extending tierods or stud screws 69. As is well known in the art, a plurality ofswitch sections 71 are mounted on tie rods 69 and contain a plurality ofcontacts which are connected into circuits to Ibe switched by the rotaryactuator. Suitable' sleeve members, such as shown at 72-74, are providedbetween the Iswitch sections 71 to space the switch sections f-rom oneanother. A Irotor shaft 75 extends longitudinally rearwardly of theactuator, and includes a portion of cylindrical cross section adjacentcasing 20, and a portion 76 of double D cross section which carries therotor sections corresponding to the switch sections 71. Bearing meansare provided for the rotary shaft in the form of an annular ange 77extending rearwardly from the mounting plate 66. Suitable detent meansare associated with the actuator, and may include a -detent member 78having a plurality of openings, each opening corresponding to oneswitching station; anda detent spring 79 carrying a ball 80 which isadapted to be seated in the openings in the detent lrotor 78 uponrotation of the shaft 75. Nuts 81 may be provided at the end of studscrews 69 to retain the elements in their assembled relationship.

The means for interrupting the flow of current to the coil 41 includes arst xed contact member 82 (FIG- URE 3), which is xedly mounted onmounting plate 66 as by rivets 83 (FIGURE 2). Contact member 82 includesa first rearwardly extending contact portion 84, which is adapted to beengaged by the movable contact to be hereafter described. Contact member82 includes a second rearwardly extending portion 85 which is adapted tobe connected in circuit with the coil 41. A movable contact member 86 ispivotally mounted on the mounting plate 66, as by a rivet 87. Contactmember 86 includes a pair of forwardly extending sides 88 and `89(FIGURE 4) which embrace the sides of a -generally V-shaped toggle link90. Toggle link 90 is formed of a suitable insulating material, andincludes an opening adjacent the apex thereof for reception of rivet 87.Contact member 86 includes a contact portion 91, which is movable intoand out of engagement with the contact portion 84 of contact member 82upon the pivotal movement of the toggle link 90.

Toggle link 90 includes a pair of diverging legs 92 and 93 which arepositioned in alignment with an arcuate slot 94 in the mounting plate66. A spring 95 is biased between the outer end of link 93, and asuitable tab 96 on a terminal 97, to urge the contact portion 91 of themovable contact 86 into engagement with the fixed contact 84. Terminal97 is tixedly mounted on mounting plate 66, as by a rivet 98, and by aforwardly extending tab 101 (FIGURE 2) which engages a suitable hole 102in the mounting plate. Terminal 97 includes a rearwardly extendingportion 99, which is adapted to be connected in circuit with the coil41; and a suitable exible lead, not shown, is connected between aforwardly extending terminal on movable contact 86 and the rearwardlyextending portion 99 on terminal 97. Thus, it is clear that when thecontact portion 91 of the movable contact 86 is in engagement with thecontact portion 84 of the iixed contact 82, a circuit is complete to thecoil 41 for energization thereof, and when the contact portion 91 movesout of engagement with the contact portion 84, this circuit isinterrupted.

The means for moving the movable contact portion 91 out of engagementwith the stationary contact portion 84 includes a generally U-shapedyoke having a central Iportion 103, and rearwardly extending arms 104and 105. Arm 105 is longer than arm 104, and extends rearwardly throughslot 94 into position for engagement with the legs 92 and 93 of thetoggle link 90. The central yoke portion 103 is provided with aneccentric hole, not shown, which receives the rearward end of drive pin58 therethrough. Suitable fastening means 106 secure the central portion103 of the yoke to the shaft 53. Thus as rotor 22 pivots when coil 41 isenergized, the drive yoke is pivoted a predetermined angular amountdetermined by the engagement of stop 62 with pin 58. As the drive yokepivots in a counterclockwise direction, as viewed in FIGURE 3, the yokearm 105 will move a certain predetermined amount before moving intocontact with the leg 93 of the toggle link. Thus, as the yoke nears theend of its angular movement, the yoke arm 105 will engage the togglellink leg 93 and pivot the toggle link 90 into an over center position.Pivotal movement of toggle link 90 moves contact portion 9'1 out ofengagement with contact portion 84, and thus the flow of current to thecoil 41 is interrupted, and the rotor 22 and the yoke are moved back totheir initial position by means to be hereafter described. Spring 95holds the toggle link 90 in the over center position while the driveyoke pivots in a clockwise direction, as viewed in FIGURE 3, apredetermined amount until the arm '5 engages the leg 92 of the togglelink, which then p-ivots the toggle link into the switch closedposition, illustrated in FIGURE 3.

A cylindrical post 107 extends forwardly from mounting plate 66, and arst hooked end 108 of a leaf spring is hooked thereover. The oppositehooked end 109 of the leaf spring is hooked over the arm 104 of thedrive yoke, to bias the same in a clockwise direction, as viewed inFIGURE 3. rl'lhus, after the drive yoke has moved the toggle link 90 toan over center position, and the flow of current to coil 41 has beeninterrupted, the leaf spring will function to return the drive yoke, thetoggle link 90, and therotor 22 to their respective initial positions.

Conventional means are provided for converting the pivoting movement ofrotor 22 into the desired increment of angular movement for rotor shaft75, and are set forth in detail in the patent to Dolesh et al., No.2,820,370. These means include a ratchet disc 110 having slotted endportions engaging yoke arms 104 and 105, and movable therewith. A secondratchet disc 111 is mounted on the rotor shaft 76, and a spring 112yieldably biases ratchet disc 110 into engagement with ratchet disc 111to effect rotation of the rotor shaft upon pivotal movement of the rotor22. An escapement cam 113 is pivotally mounted on post 107, and isprovided with an arcuate cam slot 114 through which yoke arm 104extends, to provide an overshoot control means, as described in theabove mentioned Dolesh et al. patent.

Turning now to the interrupter switch form shown in FIGURE 9, a movablecontact member 136 is pivotally mounted on a mounting plate 166 by apivot pin 187. Movable contact member 186 includes a contact portion191, which is movable into and out of engagement with the upstandingcontact portion 184 of a contact member 1182 which is fixed on themounting plate 166. A toggle link 190 includes a pair of diverging legs192 and 193 which are positioned in alignment with an arcuate slot 194in the mounting plate 166, Toggle link 190 is pivotally mounted on pivotpin 187, and is free to pivot relative to the movable contact member186. The movable contact member 186 includes a second arm 188 having athreaded hole in which a screw 120' is received. A leaf spring 121 iscarried by a pin 122 that is fixed on the mounting plate 166, andengages the outer end of the arm 188 of the movable contact 186. Acompression spring 195 is biased between the outer end of the leg 193 ofthe toggle link 190i and a stop 197 that is fixed upon the mountingplate 166 to bias the toggle link 190 in a counterclockwise direction,as viewed in FIGURE 9, It will be understood, of course, that when thecoil of the step motor is deenergized, spring 195 forces the leg 192 ofthe toggle link 190 into engagement with the movable contact portion 191to maintain the interrupter switch closed. As the drive yoke begins torotate, the drive yoke arm 205 will engage the toggle link leg 193 topivot the toggle link leg 192 out of engagement with the movable contactportion 191, as is shown in FIGURE 9. The interrupter switch will notopen until the toggle link leg 193 engages the screw 120 to initiatepivotal movement of the contact member 186, and it will be appreciatedthat as the drive yoke completes its movement toward its energizedposition, the toggle link will be moved to an Aover center position bythe yoke arm 205. In this position, the leaf spring 121 will be heldagainst a stop pin 123 which is fixed on the mounting plate 166. Thecompression spring 195 is stronger than the leaf spring 121 so that thetoggle link 190 will remain in its over center position until yoke arm205 engages the leg 192 of the toggle link 190 to move it back to itsinitial position. It will be readily appreciated that by varying theposition of screw 120 in the arrn 188 of the movable contact, the angleat which the interrupter switch opens and closes may be adjusted andcontrolled.

I claim:

1. In a rotary actuator including a casing: an electromagnet comprisingfirst and second spaced stator members, each having an openingtherethrough with a plurality of poles being provided atcircumferentially spaced points around each opening, each pole on saidfirst member being positioned in axial alignment with a correspondingpole on said second member to define a plurality of pairs of axiallyaligned stator poles; a third stator member between said first andsecond stator members and carrying an annular coil having a centralopening aligned with the openings in said first and second statormembers, said coil being wound of a length of wire having opposite ends;a terminal block carried by said third stator member and having aterminal connected to each end of the wire, said terminals being adaptedto be connected to a source of direct current; a generally cylindricalrotor mounted in the openings in said rst and second stator members andsaid coil; bearing means on said casing rotatably supporting said rotor;a plurality of axially extending poles on said rotor, each rotor polecorresponding to one of said pairs of axially aligned stator poles; stopmeans engageable with said rotor for establishing a first positionwherein each rotor pole is positioned between adjacent pairs of statorpoles when said coil is deenergized, said stop means also establishing asecond position wherein each rotor pole is positioned in radialalignment with one of'said pairs of stator poles when said coil isenergized; means for returning said rotor from said second position tosaid rst position; and means fxedly mounting said rst, second and thirdstator sections 'in said casing.

2. In a rotary actuator, a casing having front and rear walls; anelectromagnet comprising first and second spaced stator members, eachhaving an opening therethrough with a plurality of poles being providedat circumferentially spaced points around each opening, each pole onsaid first member being positioned in axial alignment with acorresponding pole on said second member to define a plurality of pairsof axially aligned stator poles; a third stator member between saidfirst and second stator members and carrying an annular coil having acentral opening aligned with the openings in said first and secondstator members, said coil being wound of a length of wire havingopposite ends; a terminal block carried by said third stator member andhaving a terminal connected to each end of the wire, said terminalsbeing adapted to be connected to a source of direct current; meansfixedly mounting ysaid first, second and third stator sections in saidcasing; a generally cylindrical rotor mounted in the openings in saidfirst and second stator members and said coil; bearing means on saidfront and rear casing walls rotatably supporting said rotor; a pluralityof axially extending poles on said rotor, each rotor pole correspondingto one of said pairs of axially aligned stator poles; stop meansengageable with said rotor for establishing a first position whereineach rotor pole is position between adjacent pairs of stator poles whensaid coil is deenergized, said stop means also establishing a secondposition wherein each rotor pole is positioned in radial alignment withone of said pairs of stator poles when said coil is energized; and meansfor returning said rotor from said second position to said firstposition.

3. In a rotary actuator, a casing having front and rear walls; anelectromagnet comprising first and second spaced :stator members, eachhaving parallel front and rear faces with an opening therethrough atright angles to said faces, a plurality of poles being provided atcircumferentially spaced points around each opening, each pole on saidfirst member being positioned in axial alignment with a correspondingpole on said second member to define a plurality of pairs of axiallyaligned stator poles, the front face of said first stator members beingpositioned against said casing front wall, and the rear face of saidsecond stator member being positioned against said casing rear Wall; athird stator member having parallel front and rear faces, with saidfront face being positioned against the rear face of said rst statormember, and said rear face positioned against the front face of saidsecond stator member; an annular coil carried by said third statormember and having a central opening aligned with the openings in saidfirst and second stator members, said coil being formed of a length ofwire having opposite ends; a terminal block carried by said third statormember and having a terminal connected to each end of the wire, saidterminals being adapted to be connected to a source of direct current;means fixedly mounting said first, second and third stator sections insaid casing; a generally cylindrical rotor mounted in the openings insaid first and second stator members and said coil, bearing means onsaid front and rear casing walls rotatably supporting said rotor, aplurality of axially extending poles on said rotor, each rotor polecorresponding to one of said pairs of axially aligned stator poles; stopmeans engageable with said rotor for establishing a first positionwherein each rotor pole is positioned between adjacent pairs of statorpoles when said coil is deenergized, said stop means also establishing asecond position wherein each rotor pole is positioned in radialalignment with `one of said pairs of stator poles when said coil isenergized; and means for returning said rotor from said second positionto said first position.

4. In a rotary actuator, a casing having front and rear walls; anelectromagnet comprising first and second spaced stator members, eachhaving parallel front and rear faces with an opening therethrough atright angles to said faces, a plurality of poles being provided atcircumferentially spaced points around each opening, each pole on saidfirst member being positioned in axial alignment with a correspondingpole on said second member to define a plurality of pairs of axiallyaligned stator poles, the front face lof said first stator member beingpositioned against said casing front wall, and the rear face of saidsecond stator member being positioned against said casing rear wall; lathird stator member having parallel front and rear faces, with saidfront face being positioned against the rear face of said first statormember, and said rear face positioned against the front face of saidsecond stator member, said third stator member having a discontinuousportion defined by spaced apart facing surfaces, aligned notches in eachsurface; an annular coil carried by said third stator .member and havinga central opening aligned with the openings in said first and secondstator members, said coil being formed of a length of wire havingopposite ends; a terminal block formed of insulating material and havinga thickness substantially the same yas the thickness of said thirdstator member, said terminal block having opposite edges, each beingslidably received in one of said notches and retained therein by theengagement of the rear face of said first stator section with one end ofsaid terminal block, and the engagement of the front face of said secondstator sec-tion with the other end of said terminal block; a pair ofterminals carried by said terminal block, each connected to one end ofsaid wire, said terminals being adapted to -be connected to a source ofdirect current; means fixedly mounting said first, second and thirdstator sections in said casing; a generally cylindrical rotor mounted inthe openings in said first and second stator members and said coil;bearing means on said casing rotatably supporting said rotor; aplurality of axially extending poles on said rotor, each rotor polecorresponding to one of said pairs of axially aligned poles; stop meansengageable with said rotor for establishing a first position whereineach rotor pole is positioned -between adjacent pairs of stator poleswhen said coil is deenergized, said stop means also establishing asecond position wherein each rotor pole is positioned in radialalignment with one of said pairs of stator poles when said coil isenergized; and means for returning said rotor from said second positionto said first position.

5. In a rotary actuator including a casing: an electromagnet comprisingfirst and second spaced stator members, each having an openingtherethrough with a plurality of poles being provided atcircumferentially spaced points around each opening, each pole on saidfirst member being positioned in axial alignment with a correspondingpole on said second member to define a plurality of pairs of axiallyaligned stator poles; a third stator member between said first landsecond stator members and carrying an annular coil having an openingaligned with the openings in said first and second stator members, saidcoil being adapted to be' connected to a source of direct current; arotor mounted in the openings in said first and second stator memberstand said coil; a plurality of axially extending poles on said rotor,each rotor pole corresponding to one of said pairs of axially alignedstator poles; stop means engageable with said rotor for establishing afirst position wherein each rotor pole is positioned between adjacentpairs of stator poles when said coil is deenergized, said stop meansalso establishing a second position wherein each rotor pole ispositioned in radial alignment with one of said pairs of stator poleswhen said coil is energized; means for returning said rotor from saidsecond position to said first position; and means fixedly mounting saidfirst, second and third stator sections in said casing.

References Cited UNITED STATES PATENTS 3,119,941 l1/1964 Guiot 310-493,153,157 10/1964 Rabe 310-156 3,204,136 8/1965 K'aiwa 310-49 3,275,8619/1966 Goroszko 310-156 MILTON O. HIRSHFIELD, Primary Examiner.

J. W. GIBBS, Assistant Examiner.

1. IN A ROTARY ACTUATOR INCLUDING A CASING: AN ELECTROMAGNET COMPRISINGFIRST AND SECOND SPACED STATOR MEMBERS, EACH HAVING AN OPENINGTHERETHROUGH WITH A PLURALITY OF POLES BEING PROVIDED ATCIRCUMFERENTIALLY SPACED POINTS AROUND EACH OPENING, EACH POLE ON SAIDFIRST MEMBER BEING POSITIONED AN AXIAL ALIGNMENT WITH A CORRESPONDINGPOLE ON SAID SECOND MEMBER TO DEFINE A PLURALITY OF PAIRS OF AXIALLYALIGNED STATOR POLES; A THIRD STATOR MEMBER BETWEEN SAID FIRST ANDSECOND STATOR MEMBERS AND CARRYING AN ANNULAR COIL HAVING A CENTRALOPENING ALIGNED WITH THE OPENINGS IN SAID FIRST AND SECOND STATORMEMBERS, SAID COIL BEING WOUND OF A LENGTH OF WIRE HAVING OPPOSITE ENDS;A TERMINAL BLOCK CARRIED BY SAID THIRD STATOR MEMBER AND HAVING ATERMINAL CONECTED TO EACH END OF THE WIRE, SAID TERMINALS BEING ADAPTEDTO BE CONNECTED TO A SOURCE OF DIRECT CURRENT; A GENERALLY CYLINDRICALROTOR MOUNTED IN THE OPENINGS IN SAID FIRST AND SECOND STATOR MEMBERSAND SAID COIL; BEARING MEANS ON SAID CASING ROTATABLY SUPPORTING SAIDROTOR; A PLURALITY OF AXIALLY EXTENDING POLES ON SAID ROTOR, EACH ROTORPOLE CORRESPONDING TO ONE OF SAID PAIRS OF AXIALLY ALIGNED STATOR POLES;STOP MEANS ENGAGEABLE WITH SAID ROTOR FOR ESTABLISHING A FIRST POSITIONWHEREIN EACH ROTOR POLE IS POSITIONED BETWEEN ADJACENT PAIRS OF STATORPOLES WHEN SAID COIL IS DEENERGIZED, SAID STOP MEANS ALSO ESTABLISHING ASECOND POSITION WHEREIN EACH ROTOR POLE IS POSITIONED IN RADIALALIGNMENT WITH ONE OF SAID PAIRS OF STATOR POLES WHEN SAID COIL ISENERGIZED; MEANS FOR RETURING SAID ROTOR FROM SAID SECOND POSITION TOSAID FIRST POSITION; AND MEANS FIXEDLY MOUNTING SAID FIRST, SECOND ANDTHIRD STATOR SECTIONS IN SAID CASING.